Method of fabricating and using an image sensor package

ABSTRACT

An image sensor package includes a molding having a locking feature. The package further includes a snap lid having a tab, where the tab is attached to the locking feature of the molding. To form the image sensor package, a window is placed in a pocket of the molding. The snap lid is secured in place. Once secured, the snap lid presses against a peripheral region of an exterior surface of the window. The window is sandwiched between the molding and the snap lid and held in place.

This application is a continuation of U.S. patent application Ser. No.09/457,516, entitled “A SNAP LID IMAGE SENSOR PACKAGE” filed on Dec. 8,1999 now U.S. Pat. No. 6,483,030.

FIELD OF THE INVENTION

The present invention relates generally to the packaging of electroniccomponents. More particularly, the present invention relates to an imagesensor package.

BACKGROUND OF THE INVENTION

Image sensors and assemblies are well known to those of skill in theart. In these assemblies, an image sensor was located within a housingwhich supported a window. Radiation passed through the window and struckthe image sensor which responded to the radiation. For the image sensorto function properly, the image sensor had to be positionally alignedwith the window to within tight positional tolerances.

Beaman et al., U.S. Pat. No. 5,821,532, hereinafter Beaman, which isherein incorporated by reference in its entirety, sets forth a printedcircuit board which included a pair of apertures used as alignmentfeatures for mounting the image sensor and for mounting the optics whichincluded the window. More particularly, the pair of apertures were usedas the mounting reference for the image sensor and then were used as themounting reference for the optics.

Formation of the assembly using the pair of apertures in the substrateas the alignment features resulted in at least three toleranceaccumulations. First, a certain tolerance was associated with theformation, or patterning, of the metallic traces on the printed circuitboard (see reference pads 14 and substrate 10 of Beaman FIG. 1). Second,a certain tolerance was associated with the placement of the imagesensor on the substrate (see images sensor 32 and substrate 10 of BeamanFIG. 3). Third, a certain tolerance was associated the placement of theoptics on the substrate (see Beaman FIG. 4).

After the image sensor assembly was constructed, the lens assembly wasplaced over the image sensor assembly. The lens assembly was used tofocus light on the image sensor. Typically, the lens assembly wasattached directly to the substrate after the image sensor assembly wasattached to the substrate. After attachment, the lens assembly wasadjusted, for example with adjustment screws, to move the lens assemblyuntil the proper focus was attained. This very rough adjustment waslabor intensive. Further, a large tolerance was associated with thisvery rough adjustment.

Disadvantageously, the image sensor assembly had to accommodate thetolerances discussed above. However, as the art moves to smaller,lighter and less expensive devices, the acceptable tolerances for imagesensor assemblies diminishes.

In conventional image sensor assemblies, a housing was used to supportthe window and to hermetically seal the image sensor (see housing 24 andwindow 25 of Beaman FIG. 4 for example). This housing was typicallyformed of ceramic which advantageously had excellent resistance tomoisture transmission to protect the image sensor from the ambientenvironment. Further, the ceramic housing was formed with a shelf whichheld the window and facilitated proper height positioning of the window(see shelf 29 and window 25 of Beaman FIG. 4 for example). However,ceramic is relatively expensive compared to other conventional packagingmaterials and it is important to form the image sensor assembly at a lowcost.

In addition, mounting this housing at the printed circuit board levelwas inherently labor intensive and made repair or replacement of theimage sensor difficult. In particular, removal of the housing exposedthe image sensor to the ambient environment. Since the image sensor wassensitive to dust as well as other environmental factors, it wasimportant to make repairs or replacement of the image sensor in acontrolled environment such as a clean room. Otherwise, there was a riskof damaging or destroying the image sensor. Since neither of thesealternatives are desirable and both are expensive, the art needs animage sensor assembly which is simple to manufacture and service so thatcosts associated with the image sensor assembly are minimized.

SUMMARY OF THE INVENTION

In accordance with the present invention, a plurality of image sensorpackages are fabricated simultaneously to minimize the cost associatedwith each individual image sensor package. To fabricate the image sensorpackages, a plurality of windows are placed in a mold. Molding compoundis transferred to the mold to form a plurality of moldings, each of themoldings enclosing a corresponding window. The moldings are integrallyconnected together by bridge sections. After molding the windows in themolding compound, a molded window array, which includes the windowsmolded in corresponding moldings, is removed from the mold.

A substrate includes a plurality of individual substrates integrallyconnected together in an array format. Image sensors are attached tocorresponding individual substrates. Bond pads of the image sensors areelectrically connected to corresponding traces of the individualsubstrates.

The molded window array is aligned with the substrate such that eachmolding is precisely positioned with respect to the corresponding imagesensor. After alignment, the molded window array is brought intoabutting contact with an upper surface of the substrate such that anadhesive layer attaches the molded window array to the substrate. In oneembodiment, the moldings are marked and a lower surface of the substrateis populated with interconnection balls. The substrate and attachedmolded window array are singulated into a plurality of individual imagesensor packages.

By forming a plurality of image sensor packages simultaneously, severaladvantages are realized. One advantage is that it is less laborintensive to handle and process a plurality of image sensor packagessimultaneously rather than to handle and process each image sensorpackage on an individual basis. Another advantage is that usage ofmaterials is more efficient when a plurality of image sensor packagesare fabricated simultaneously. By reducing labor and using lessmaterial, the cost associated with each image sensor package isminimized.

Of importance, the molding of the image sensor package is a low costmolded part. Advantageously, the molding is significantly less expensivethan housings of the prior art which were typically ceramic.Accordingly, the image sensor package in accordance with the presentinvention is significantly less expensive to manufacture than imagesensor assemblies of the prior art.

By forming the molding of the image sensor package as a molded part, adistance, sometimes called the Z height, between the window and theimage sensor is precisely controlled to within tight tolerance.

Recall that in the prior art, the window was placed on a shelf of ahousing after the housing was fabricated. Since a significant tolerancewas associated with the window placement, the distance between thewindow and the image sensor had significant variations from assembly toassembly. However, to insure optimum operation of the image sensor, itis important that the distance between the window and the image sensorbe precise. Since the tolerance in this distance is reduced in an imagesensor package in accordance with the present invention, the performanceof an image sensor package in accordance with the present invention issuperior to that of the prior art.

In one embodiment, the molding of the image sensor package includes aplurality of alignment notches. These alignment notches are used toalign a lens to the image sensor.

Use of the alignment notches facilitates alignment of the lens to theimage sensor. As discussed above, the molding is precisely aligned tothe image sensor. Advantageously, this allows the lens to be preciselyaligned to the image sensor in a single operation by aligning the lensto the alignment notches. Accordingly, alignment of the lens to theimage sensor in accordance with the present invention is relativelysimple. This is in contrast to the prior art, which required a firstalignment of the image sensor to the larger substrate and a secondalignment of the optics to the larger substrate.

Enviro-hermetically sealing the image sensor in accordance with thepresent invention also reduces complexity and cost in the event theimage sensor must be replaced compared to the prior art. As used herein,the term “enviro-hermetically sealed” means sealed sufficiently toprevent environmental degradation, e.g., from dust or moisture, of theimage sensor package and, more particularly, of the image sensor.

Recall that in the prior art, the housing which hermetically sealed theimage sensor was mounted directly to the larger substrate. Thus, removalof the housing necessarily exposed the image sensor to the ambientenvironment and to dust. For this reason, the image sensor had torepaired or replaced in a cleanroom or else there was a risk of damagingor destroying the image sensor.

In contrast, the image sensor is enviro-hermetically sealed as part ofthe image sensor package in accordance with the present invention. Theimage sensor package is mounted to the larger substrate, for example, byreflowing interconnection balls. To replace the image sensor, the imagesensor package is simply removed and a new image sensor package ismounted to the larger substrate. At no time is the image sensor exposedto the ambient environment during this procedure. Advantageously, thisprocedure can be performed in any facility with or without a cleanroom.

The old image sensor package is discarded or shipped to a centralfacility for repair. Since the image sensor package is simple tomanufacture and service, the costs associated with the image sensorpackage are minimized compared to the prior art.

In one embodiment, an image sensor package includes a molding having aninterior locking feature and an exterior locking feature. The molding isintegral, i.e., is one piece and not a plurality of separate piecesconnected together. The image sensor package further includes a windowhaving an interior surface and an exterior surface. The exterior lockingfeature of the molding contacts a periphery of the exterior surface ofthe window and the interior locking feature of the molding contacts aperiphery of the interior surface of the window.

By having the molding extend over the peripheries of the exterior andinterior surfaces of the window, the distance which moisture must travelalong the interface between the molding and the window to reach theimage sensor is maximized thus essentially eliminating moisture ingressinto the image sensor package.

In another embodiment, an image sensor package includes a window and amolding, where the molding includes a lens holder extension portionextending upwards, e.g., in a first direction perpendicular to theexterior surface of the window, from the window. The lens holderextension portion includes a female threaded aperture extending upwardsfrom the window such that the window is exposed through the aperture.

A lens is supported in a lens support. The lens support has a threadedexterior surface. The lens support is threaded into the aperture of thelens holder extension portion.

Advantageously, the lens is readily adjusted relative to the imagesensor by rotating the lens support. More particularly, the lens supportis rotated around a longitudinal axis of the lens support in a firstdirection, e.g., clockwise looking down at the lens support, to move thelens support and the lens towards the image sensor. Conversely, the lenssupport is rotated around the longitudinal axis in a second directionopposite the first direction, e.g., counterclockwise looking down at thelens support, to move the lens support and the lens away from the imagesensor. In this manner, the lens support is rotated until radiationpassing through the lens is properly focused on an active area of theimage sensor. Once proper focus is attained, the lens support isprevented from unintentional rotation. For example, adhesive is appliedto secure the lens support to the molding.

Recall that in the prior art, the lens assembly was typically attacheddirectly to the larger substrate, such as a printed circuit motherboard, after the image sensor assembly was attached to the largersubstrate. A large tolerance was associated with attachment of the lensassembly in this manner. However, it is important to reduce tolerancebuildup to optimize performance of the image sensor assembly.

Further, the lens assembly of the prior art typically had to be adjustedby moving the lens assembly relative to the larger substrate, forexample with adjustment screws. Undesirably, this was labor intensivewhich increased the cost of the electronic device which used the imagesensor assembly.

In addition, the lens assembly of the prior art was sometimesinadvertently moved relative to the image sensor which caused defocusingand defective operation of the image sensor. For example, the lensassembly was sometimes bumped during assembly or servicing of theelectronic device which used the image sensor assembly. As anotherexample, the lens assembly moved due to warpage of the larger substrate.

Advantageously, the image sensor package in accordance with the presentinvention eliminates these problems of the prior art. In particular,since the molding including the lens holder extension portion isprecisely positioned with respect to the image sensor, the position ofthe lens with respect to the image sensor is also precise to withintight tolerance. Reducing tolerance in the position of the lens withrespect to the image sensor improves performance of the image sensorpackage compared to prior art image sensor assemblies.

Further, the lens is adjusted relative to the image sensor simply byrotating the lens support thus readily allowing focusing of radiation onthe active area of the image sensor. Advantageously, this focusing isperformed during fabrication of the image sensor package before assemblyto the larger substrate. Thus, the prior art requirement of focusing thelens assembly during assembly of the larger substrate is eliminated. Asa result, the costs associated with the image sensor package is lowerthan that associated with prior art image sensor assemblies.

Further, since the lens support and the lens are integrated into theimage sensor package, there is essentially no possibility ofinadvertently moving the lens relative to the image sensor. Thus theprior art possibility of bumping the lens assembly or otherwise havingthe lens assembly move and defocus the radiation is eliminated.

In another embodiment, an image sensor package includes a molding havinga locking feature. The package further includes a snap lid having a tab,where the tab is attached to the locking feature of the molding.

To form the image sensor package, after the molding is fabricated, awindow is placed in a pocket of the molding. A shelf of the moldingcontacts and supports a peripheral region of an interior surface of thewindow. The snap lid is secured in place. Once secured, the snap lidpresses against a peripheral region of an exterior surface of thewindow.

Of importance, the window is sandwiched between the molding and the snaplid. In this manner, the window is held in place. Advantageously, use ofthe snap lid allows the window to be kept in a protective wrapper untilthe window is needed. For example, the window is kept in a protectivewrapper to avoid contamination or scratching of the window.

As a further advantage, use of the snap lid allows the window to beeasily removed. Once removed, the window is easily cleaned, treated orreplaced with a different window.

Also in accordance with the invention, a molded window array includes aplurality of moldings integrally connected together and a plurality ofwindows. Each window of the plurality of windows is support in acorresponding molding of the plurality of moldings.

These and other features and advantages of the present invention will bemore readily apparent from the detailed description set forth belowtaken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an image sensor package inaccordance with the present invention.

FIG. 2 is a cross-sectional view of the package taken along the lineII—II of FIG. 1.

FIG. 3 is an upper perspective view of windows in cavities of a lowermold half of a mold in accordance with the present invention.

FIG. 4 is a cross-sectional view along the line IV—IV of FIG. 3.

FIG. 5 is a cross-sectional view of the mold of FIGS. 3, 4 at a laterstage of fabrication.

FIG. 6 is a cross-sectional view of the mold of FIG. 5 at a later stageof fabrication.

FIG. 7A is an enlarged cross-sectional view of the region VII of FIG. 6in accordance with one embodiment of the present invention.

FIG. 7B is an enlarged cross-sectional view of the region VII of FIG. 6in accordance with another embodiment of the present invention.

FIG. 7C is an enlarged cross-sectional view of the region VII of FIG. 6in accordance with yet another embodiment of the present invention.

FIG. 8 is a cross-sectional view of an array of image sensor packagesduring assembly in accordance with the present invention.

FIG. 9 is a cross-sectional view of the array of image sensor packagesof FIG. 8 at a later stage of fabrication in accordance with the presentinvention.

FIG. 10A is an enlarged cross-sectional view of the region X of FIG. 6in accordance with one embodiment of the present invention.

FIG. 10B is an enlarged perspective view, partially in cross-section, ofthe region X of FIG. 6 in accordance with an alternative embodiment ofthe present invention.

FIG. 11 is a perspective view, partially cutaway and partially exploded,of an image sensor package in accordance with another embodiment of thepresent invention.

FIG. 12 is a cross-sectional view of the package taken along the lineXII—XII of FIG. 11.

FIG. 13 is a cross-sectional view of a molded window array in accordancewith one embodiment of the present invention.

FIG. 14 is an enlarged cross-sectional view of the region XIV of FIG.13.

FIG. 15 is an exploded perspective view of an image sensor package inaccordance with another embodiment of the present invention.

FIG. 16 is a cross-sectional view of the package taken along the lineXVI—XVI of FIG. 15.

FIG. 17 is a cross-sectional view of the package of FIGS. 15 and 16illustrating the attachment of a snap lid to a molding.

FIG. 18A is an enlarged cross-sectional view of the region XVIII of thepackage of FIG. 16 in accordance with one embodiment of the presentinvention.

FIG. 18B is an enlarged cross-sectional view of the region XVIII of thepackage of FIG. 16 in accordance with an alternative embodiment of thepresent invention.

In the following description, similar elements are labeled with similarreference numbers.

DETAILED DESCRIPTION

In accordance with the present invention, a plurality of image sensorpackages 100 (FIGS. 1, 2) are fabricated simultaneously to minimize thecost associated with each individual package 100. To fabricate packages100, a plurality of windows 122 are placed in a mold which includesupper and lower mold halves 300, 500 (FIG. 5). Molding compound istransferred to the mold to form a plurality of moldings 124 (FIG. 6),each of moldings 124 enclosing a corresponding window 122. Moldings 124are integrally connected together by bridge sections 602. After moldingwindows 122 in the molding compound, a molded window array 802 (FIG. 8),which includes windows 122 molded in corresponding moldings 124, isremoved from the mold.

A substrate 810 (FIG. 8) includes a plurality of individual substrates102 integrally connected together in an array format. Image sensors 106are attached to corresponding substrates 102. Bond pads 112 of imagesensors 106 are electrically connected to corresponding traces 104 ofcorresponding substrates 102 with corresponding bond wires 114.

Molded window array 802 is aligned with substrate 810 such that eachmolding 124 is precisely positioned with respect to a correspondingimage sensor 106. After alignment, molded window array 802 is broughtinto abutting contact with an upper surface 810U of substrate 810 suchthat an adhesive layer 126 attaches molded window array 802 to substrate810 as shown in FIG. 9. In one embodiment, moldings 124 are marked and alower surface 810L of substrate 810 is populated with interconnectionballs 218. Substrate 810 and attached molded window array 802 aresingulated into a plurality of individual packages 100.

Referring to FIGS. 1 and 2 together, by forming a plurality of packages100 simultaneously, several advantages are realized. One advantage isthat it is less labor intensive to handle and process a plurality ofpackages 100 simultaneously rather than to handle and process eachpackage 100 on an individual basis. Another advantage is that usage ofmaterials is more efficient when a plurality of packages 100 arefabricated simultaneously. By reducing labor and using less material,the cost associated with each package 100 is minimized.

Of importance, molding 124 is a low cost molded part. Advantageously,molding 124 is significantly less expensive than housings of the priorart which were typically ceramic. Accordingly, package 100 in accordancewith the present invention is significantly less expensive tomanufacture than image sensor assemblies of the prior art.

By forming molding 124 as a molded part, a distance ZH, sometimes calledthe Z height, between window 122 and image sensor 106 is preciselycontrolled to within tight tolerance.

Recall that in the prior art, the window was placed on a shelf of ahousing after the housing was fabricated. Since a significant tolerancewas associated with the window placement, the distance between thewindow and the image sensor had significant variations from assembly toassembly. However, to insure optimum operation of the image sensor, itis important that the distance between the window and the image sensorbe precise. Since the tolerance in this distance is reduced in package100, the performance of package 100 is superior to that of the priorart.

In one embodiment, molding 124 of package 100 includes a plurality ofalignment notches 130. Alignment notches 130 are used to align a lens(not shown) to image sensor 106.

Use of alignment notches 130 facilitates alignment of the lens to imagesensor 106. As discussed above, molding 124 is precisely aligned toimage sensor 106. Advantageously, this allows the lens to be preciselyaligned to image sensor 106 in a single operation by aligning the lensto alignment notches 130. Accordingly, alignment of the lens to imagesensor 106 is relatively simple. This is in contrast to the prior art,which required a first alignment of the image sensor to the largersubstrate and a second alignment of the optics to the larger substrate.

Enviro-hermetically sealing image sensor 106 in accordance with thepresent invention also reduces complexity and cost in the event imagesensor 106 must be repaired or replaced compared to the prior art.Recall that in the prior art, the housing which hermetically sealed theimage sensor was mounted directly to the larger substrate. Thus, removalof the housing necessarily exposed the image sensor to the ambientenvironment and to dust. For this reason, the image sensor had to berepaired or replaced in a cleanroom or else there was a risk of damagingor destroying the image sensor.

In contrast, image sensor 106 is enviro-hermetically sealed as part ofpackage 100. Package 100 is mounted to the larger substrate, forexample, by reflowing interconnection balls 218. To repair or replaceimage sensor 106, package 100 is simply removed and a new package 100 ismounted to the larger substrate. At no time is image sensor 106 exposedto the ambient environment during this procedure. Advantageously, thisprocedure can be performed in any facility with or without a cleanroom.The old package 100 is discarded or shipped to a central facility forrepair. Since package 100 is simple to manufacture and service, thecosts associated with package 100 are minimized compared to the priorart.

In one embodiment, molding 124 has an interior locking feature 225I andan exterior locking feature 225E. Molding 124 is integral, i.e., is onepiece and not a plurality of separate pieces connected together. Window122 has an interior surface 122I and an exterior surface 122E. Exteriorlocking feature 225E of molding 124 contacts a periphery of exteriorsurface 122E of window 122 and interior locking feature 225I of molding124 contacts a periphery of interior surface 122I of window 122.

By having molding 124 extend over peripheries of exterior and interiorsurfaces 122E, 122I of window 122, the distance which moisture musttravel along the interface between molding 124 and window 122 to reachimage sensor 106 is maximized thus essentially eliminating moistureingress into package 100.

In another embodiment, an image sensor package 1100 (FIGS. 11, 12)includes window 122 and a molding 124C, where molding 124C includes alens holder extension portion 1102 extending upwards, e.g., in a firstdirection, from window 122. Lens holder extension portion 1102 includesa female threaded aperture 1106 extending upwards from window 122 suchthat window 122 is exposed through aperture 1106.

A lens 1210 is supported in a lens support 1112. Lens support 1112 has athreaded exterior surface 1120. Lens support 1112 is threaded intoaperture 1106 of lens holder extension portion 1102.

Advantageously, lens 1210 is readily adjusted relative to image sensor106 by rotating lens support 1112. More particularly, lens support 1112is rotated around a longitudinal axis 1218 of lens support 1112 in afirst direction, e.g., clockwise looking down at lens support 1112, tomove lens support 1112 and lens 1210 towards image sensor 106.Conversely, lens support 1112 is rotated around longitudinal axis 1218in a second direction opposite the first direction, e.g.,counterclockwise looking down at lens support 1112, to move lens support1112 and lens 1210 away from image sensor 106. In this manner, lenssupport 1112 is rotated until radiation passing through lens 1210 isproperly focused on an active area 110 of image sensor 106. Once properfocus is attained, lens support 1112 is prevented from unintentionalrotation. For example, adhesive is applied to secure lens support 1112to molding 124C.

Recall that in the prior art, the lens assembly was typically attacheddirectly to the larger substrate, such as a printed circuit motherboard, after the image sensor assembly was attached to the largersubstrate. A large tolerance was associated with attachment of the lensassembly in this manner. However, it is important to reduce tolerance tooptimize performance of the image sensor assembly.

Further, the lens assembly of the prior art typically had to be adjustedby moving the lens assembly relative to the larger substrate, forexample with adjustment screws. Undesirably, this was labor intensivewhich increased the cost of the electronic device which used the imagesensor assembly.

In addition, the lens assembly of the prior art was sometimesinadvertently moved relative to the image sensor which caused defocusingand defective operation of the image sensor. For example, the lensassembly was sometimes bumped during assembly or servicing of theelectronic device which used the image sensor assembly. As anotherexample, the lens assembly moved due to warpage of the larger substrate.

Advantageously, package 1100 in accordance with the present inventioneliminates these problems of the prior art. In particular, since molding124C including lens holder extension portion 1102 is preciselypositioned with respect to image sensor 106, the position of lens 1210with respect to image sensor 106 is also precise to within tighttolerance. Reducing tolerance in the position of lens 1210 with respectto image sensor 106 improves performance of package 1100 compared toprior art image sensor assemblies.

Further, lens 1210 is adjusted relative to image sensor 106 simply byrotating lens support 1112 thus readily allowing focusing of radiationon active area 110 of image sensor 106. Advantageously, this focusing isperformed during fabrication of package 1100 before assembly to thelarger substrate. Thus, the prior art requirement of focusing the lensassembly during assembly of the larger substrate is eliminated. As aresult, the costs associated with package 1100 are lower than thoseassociated with prior art image sensor assemblies.

Further, since lens support 1112 and lens 1210 are integrated intopackage 1100, there is essentially no possibility of inadvertentlymoving lens 1210 relative to image sensor 106. Thus, the prior artpossibility of bumping the lens assembly or otherwise having the lensassembly move and defocus the radiation is eliminated.

In another embodiment, an image sensor package 1500 (FIGS. 15, 16)includes a molding 124D having a locking feature 1508. Package 1500further includes a snap lid 1502 having a tab 1612, where tab 1612 isattached to locking feature 1508 of molding 124D.

To form package 1500, after molding 124D is fabricated, a window 122C isplaced in a pocket 1800 (FIG. 18A) of molding 124D. A shelf 1804 ofmolding 124D contacts and supports a peripheral region 122IPR of aninterior surface 122I of window 122C. Snap lid 1502 is secured in place.Once secured, snap lid 1502 presses against a peripheral region 122EPRof an exterior surface 122E of window 122C.

Of importance, window 122C is sandwiched between molding 124D and snaplid 1502. In this manner, window 122C is held in place. Advantageously,use of snap lid 1502 allows window 122C to be kept in a protectivewrapper until window 122C is needed. For example, window 122C is kept ina protective wrapper to avoid contamination or scratching of window122C.

As a further advantage, use of snap lid 1502 allows window 122C to beeasily removed. Once removed, window 122C is easily cleaned, treated orreplaced with a different window.

More particularly, FIG. 1 is an exploded perspective view of an imagesensor package 100 in accordance with the present invention. FIG. 2 is across-sectional view of package 100 taken along the line II—II of FIG.1. Referring to FIGS. 1 and 2 together, package 100 includes a substrate102 such as an alumina-based ceramic substrate, a printed circuit boardsubstrate, a plastic glass laminated substrate, or a tape-basedsubstrate. Attached to an upper, e.g., first, surface 102U of substrate102 is an image sensor 106. Illustratively, image sensor 106 is a CMOSimage sensor device, a charge coupled device (CCD), or a pyroelectricceramic on CMOS device although other image sensors are used in otherembodiments.

In this embodiment, a lower, e.g. first, surface 106L of image sensor106 is attached by an adhesive layer 108 to upper surface 102U ofsubstrate 102 although other attachment techniques and/or materials,such as solder, are used in other embodiments. A metallization 109 onupper surface 102U defines a die attach area of substrate 102 to whichimage sensor 106 is attached.

Image sensor 106 includes an active area 110 on an upper, e.g., second,surface 106U of image sensor 106. Generally, active area 110 isresponsive to radiation, e.g., electromagnetic radiation, as is wellknown to those of skill in the art. For example, active area 110 isresponsive to infrared radiation, ultraviolet light, and/or visiblelight.

Image sensor 106 further includes a plurality of bond pads 112 on uppersurface 106U of image sensor 106. Bond pads 112 are connected tointernal circuitry of image sensor 106.

Substrate 102 includes a plurality of electrically conductive traces 104formed on upper surface 102U of substrate 102. Bond pads 112 areelectrically connected to corresponding traces 104 by bond wires 114.

As shown in FIG. 2, traces 104 are electrically connected tocorresponding electrically conductive vias 215 which extend from uppersurface 102U to a lower, e.g., second, surface 102L of substrate 102.Vias 215 are electrically connected to corresponding electricallyconductive traces 216 on lower surface 102L of substrate 102. Formed ontraces 216 are corresponding electrically conductive pads 217. Formed onpads 217 are corresponding electrically conductive interconnection balls218 such as solder balls. Interconnection balls 218 are used toelectrically connect package 100 to a larger substrate (not shown) suchas a printed circuit mother board.

To illustrate, a first bond pad 112A of the plurality of bond pads 112is electrically connected to a first trace 104A of the plurality oftraces 104 by a first bond wire 114A of a plurality of bond wires 114.Trace 104A is electrically connected to a first via 215A of theplurality of vias 215. Via 215A is electrically connected to a firsttrace 216A of the plurality of traces 216. A first conductive pad 217Aof the plurality of conductive pads 217 is formed on trace 216A. Formedon pad 217A is a first interconnection ball 218A of the plurality ofinterconnection balls 218.

As set forth above, an electrically conductive pathway between bond pad112A and interconnection ball 218A is formed by bond wire 114A, trace104A, via 215A, trace 216A and pad 217A. The other bond pads 112, bondwires 114, traces 104, vias 215, traces 216, pads 217 andinterconnection balls 218 are electrically connected to one another in asimilar fashion so are not discussed further to avoid detracting fromthe principals of the invention.

Although a particular electrically conductive pathway betweeninterconnection ball 218A and bond pad 112A is described above, in lightof this disclosure, it is understood that other electrically conductivepathways can be formed. For example, substrate 102 is a multi-layeredlaminated substrate and, instead of straight-through vias 215, aplurality of electrically conductive traces on various layers insubstrate 102 are interconnected by a plurality of electricallyconductive vias to form the electrical interconnections between traces104 and 216.

As a further example, vias 215 extend along sides 102S of substrate 102and traces 104 and 106 extend to sides 102S. As another alternative,interconnection balls 218 are distributed in an array format to form aball grid array type package. Alternatively, interconnection balls 218are not formed, e.g., to form a metal land array type package or aleadless chip carrier (LCC) package. Other electrically conductivepathway modifications will be obvious to those of skill in the art.

Further, although a particular number of bond pads 112, traces 104 andbond wires 114 are illustrated in FIG. 1, i.e., twenty of each, it isunderstood that more or less bond pads 112, traces 104, bond wires 114,vias 215, traces 216, pads 217 and interconnection balls 218 aretypically used depending upon the particular input/output requirementsof image sensor 106.

Package 100 further includes an optical lid 120, which includes a window122 and a molding 124. Generally, window 122 is transparent to theradiation of interest, e.g. to the radiation to which active area 110 ofimage sensor 106 is responsive. In this embodiment, window 122 isoptical glass, germanium or silicon but can be formed of other materialsdepending upon the application.

In one embodiment, window 122 includes one or more filters such as aninfrared filter, although in other embodiments window 122 does notinclude a filter. Window 122 is typically planar and has no opticalpower, although in one embodiment, window 122 has optical power, e.g.,is a lens. Window 122 is located above active area 110 of image sensor106. It is understood that the term “above” and similar terms are usedgenerally and are not necessarily related to a gravitational reference,e.g., package 100 can be inverted without affecting the operation ofpackage 100.

Window 122 is supported by molding 124. Molding 124 is formed of amolding material having excellent adhesion to window 122. Tomechanically lock window 122 in place, molding 124 extends inwardsbeyond sides 122S of window 122. More particularly, an exterior lockingfeature 225E of molding 124 extends over and contacts a periphery of anexterior surface 122E of window 122 and an interior locking feature 225Iof molding 124 extends over and contacts a periphery of an interiorsurface 122I of window 122. As used herein, the periphery of exteriorsurface 122E, interior surface 122I is the portion of exterior surface122E, interior surface 122I, respectively, directly adjacent sides 122Sof window 122. Sides 122S extend between exterior surface 122E andinterior surface 122I.

Thus, molding 124 mechanically locks window 122 in place both top andbottom. Although molding 124 extends over the peripheries of exteriorand interior surfaces 122E, 122I, in alternative embodiments, molding124 extends over and contacts a periphery of only exterior surface 122Eor, alternatively, only interior surface 122I. As a further alternative,molding 124 contacts sides 122S only and does not extend over eitherinterior surface 122I or exterior surface 122E.

Optical lid 120, and more particularly, a base 226 of molding 124 isattached to a periphery of upper surface 102U of substrate 102 byadhesive layer 126. Thus, image sensor 106 is located andenviro-hermetically sealed in an enclosure formed by substrate 102,optical lid 120 and adhesive layer 126. As used herein, the term“enviro-hermetically sealed” means sealed sufficiently to preventenvironmental degradation, e.g., from dust or moisture, of package 100and, more particularly, of image sensor 106. By enviro-hermeticallysealing image sensor 106, image sensor 106 is protected from the ambientenvironment, e.g., dust and moisture.

To further enhance moisture protection of image sensor 106, molding 124is formed of a material which is highly resistant to moisture. Inaddition, by having molding 124 extend over the peripheries of exteriorand interior surfaces 122E, 122I of window 122, the distance whichmoisture must travel along the interface between molding 124 and window122 to reach image sensor 106 is maximized thus further preventingmoisture ingress into package 100.

Of importance, molding 124 is a low cost molded part formed of moldingcompound. Advantageously, molding 124 is significantly less expensivethan housings of the prior art which were typically ceramic.Accordingly, package 100 is significantly less expensive to manufacturethan image sensor assemblies of the prior art.

By forming molding 124 as a molded part, a distance ZH, sometimes calledZ height ZH, between interior surface 122I of window 122 and uppersurface 106U of image sensor 106 is precisely controlled. In oneembodiment, distance ZH is 0.040 inches (1.016 mm) and the toleranceassociated with distance ZH is 0.001 inches (0.025 mm).

Recall that in the prior art, the window was placed on a shelf of ahousing after the housing was fabricated. Since a significant tolerancewas associated with the window placement, the distance between thewindow and the image sensor had significant variations from assembly toassembly. However, to insure optimum operation of the image sensor, itis important that the distance between the window and the image sensorbe precise. Since the tolerance in this distance is reduced in package100 compared to the prior art, the performance of package 100 issuperior to that of the prior art.

As best shown in FIG. 1, molding 124 includes a plurality of alignmentnotches 130 which are used to align an optical axis of a lens (notshown) to the optical center of active area 110 of image sensor 106.This alignment is generally referred to as aligning a lens to imagesensor 106. Although three alignment notches 130 are illustrated, moreor less than three alignment notches 130 are used in alternativeembodiments.

Use of alignment notches 130 facilitates alignment of the optical axisof the lens to the optical center of active area 110. As discussedfurther below, molding 124 is aligned to image sensor 106 and, moreparticularly, to the optical center of active area 110, to within tightpositional tolerances. Advantageously, this allows the optical axis ofthe lens to be aligned to within tight positional tolerances, e.g.,0.001 inches (0.025 mm), to the optical center of active area 110 in asingle operation by aligning the optical axis of the lens to alignmentnotches 130. Accordingly, alignment of the optical axis of the lens tothe optical center of active area 110 is relatively simple compare tothe prior art, which required a first alignment of the image sensor tothe larger substrate and a second alignment of the optics to the largersubstrate.

Enviro-hermetically sealing image sensor 106 also reduces complexity andcost in the event image sensor 106 must be repaired or replaced. Recallthat in the prior art, the housing which hermetically sealed the imagesensor was mounted directly to the larger substrate. Thus, removal ofthe housing necessarily exposed the image sensor to the ambientenvironment and to dust. As a result, the image sensor had to repairedor replaced in a cleanroom or else there was a risk of damaging ordestroying the image sensor.

In contrast, image sensor 106 is enviro-hermetically sealed as part ofpackage 100. Package 100 is mounted to the larger substrate, forexample, by reflowing interconnection balls 218 as is well known tothose of skill in the art. To repair or replace image sensor 106,package 100 is simply removed and a new package 100 is mounted to thelarger substrate. At no time is image sensor 106 exposed to the ambientenvironment during this procedure. Advantageously, this procedure can beperformed in any facility with or without a cleanroom. The old package100 is discarded or shipped to a central facility for repair. Sincepackage 100 is simple to manufacture and service, the costs associatedwith package 100 are minimized compared to the prior art.

In one embodiment, package 100 is fabricated simultaneously with aplurality of packages 100 to minimize the cost associated with eachindividual package 100. In accordance with this embodiment, FIG. 3 is anupper perspective view of a plurality of windows 122 in a plurality ofcavities 302 of a lower, e.g., first, mold half 300 of a mold and FIG. 4is a cross-sectional view along the line IV—IV of FIG. 3.

Referring to FIGS. 3 and 4 together, lower mold half 300 defines a threeby three (3×3) array of cavities 302 for a total of nine cavities 302,all of which are similar. Although a mold having a three by three arrayof cavities 302 is set forth, in light of this disclosure, it isunderstood that a mold having more or less than a three by three arrayof cavities 302 is used to form more or less, respectively, than ninepackages simultaneously.

Positioned in a first cavity 302A of the plurality of cavities 302 is afirst window 122A of a plurality of windows 122. Each of the otherwindows 122 is similarly placed in a corresponding cavity 302 so thateach of the nine cavities 302 contains one of windows 122. The placementof an article into a mold cavity is well known to those of skill in theart.

A plurality of tabs 304A protrude from lower mold half 300 into firstcavity 302A. In this embodiment, three tabs 304A exist, but only one tab304A is visible in the views of FIGS. 3 and 4. A set of tabs 304protrude into each of the other cavities 302 in a similar manner. Tabs304 which include tabs 304A result in the formation of alignment notches130 (see FIGS. 1, 2) as discussed further below.

FIG. 5 is a cross-sectional view of the mold of FIGS. 3, 4 at a laterstage of fabrication. After windows 122 are positioned in cavities 302in lower mold half 300, an upper, e.g., second, mold half 500 (FIG. 5)is brought down on lower mold half 300 and into the closed position.

As shown in FIG. 5, upper mold half 500 includes a plurality ofextensions 502, all of which are similar, including a first extension502A. Extension 502A is substantially the inverse shape of cavity 302Aand extends downwards from the main body 501 of upper mold half 500.Thus, when upper mold half 500 is in a closed position adjacent lowermold half 300 as illustrated in FIG. 5, extension 502A extends intocavity 302A and presses against window 122A. More particularly, a base504A of extension 502A presses against interior surface 122I of window122A and a base 306A which defines cavity 302A of lower mold half 300presses against exterior surface 122E of window 122A. The otherextensions 502 similarly press against the other windows 122.

Further, when upper mold half 500 is in the closed position asillustrated in FIG. 5, upper mold half 500 and lower mold half 300define a space 506 between upper mold half 500 and lower mold half 300which is filled with molding compound as shown in FIG. 6.

FIG. 6 is a cross-sectional view of the mold of FIG. 5 at a later stageof fabrication. As shown in FIG. 6, molding compound is transferred intospace 506 (FIG. 5) to form moldings 124. The transfer of moldingcompound into a mold is well known to those of skill in the art. As anexample, a molding compound is heated to a melt and then forced betweenupper mold half 500 and lower mold half 300. After being transferred tothe mold, i.e., upper mold half 500 and lower mold half 300, the moldingcompound is allowed to cool and solidify.

Generally, the molding compound should be mechanically stable over alltemperatures to which package 100 may be heated. For example, themolding compound should be mechanically stable at the temperature whichpackage 100 is heated during attachment to the larger substrate such asthe printed circuit mother board. As an illustration, the moldingcompound is mechanically stable when heated to 220° C. for one minute.Suitable molding compounds are available from Amoco PerformanceProducts, Inc. located in Atlanta, Ga., e.g., A-100, A-200, A-300,R-5000, R-5100, R-5700 resins.

A first molding 124A of the plurality of moldings 124 encloses window122A and surrounds extension 502A. The other moldings 124 similarlyenclose corresponding windows 122 and surround corresponding extensions502. Of importance, by molding windows 122 in moldings 124 using upperand lower mold halves 500, 300, windows 122 are precisely positioned inmoldings 124 to within tight tolerance, e.g., to within 0.001 in. (0.025mm). As discussed above in reference to FIG. 2, this allows the Z heightZH to be precisely controlled which ensures optimum performance ofpackage 100. This is in contrast to the prior art where placement of thewindow on the shelf of the housing after the housing was fabricatedresulted in significant variations in the position of the window fromassembly to assembly.

The plurality of moldings 124 are integrally connected together. Moreparticularly, bridge sections 602 of molding compound integrally connectadjacent moldings 124. To illustrate, a first bridge section 602A of theplurality of bridge sections 602 integrally connects first molding 124Ato an adjacent second molding 124B of the plurality of moldings 124.

FIG. 7A is an enlarged cross-sectional view of the region VII of FIG. 6in accordance with one embodiment of the present invention. As shown inFIG. 7A, base 504A presses directly on interior surface 122I of window122A and base 306A presses directly on exterior surface 122E of window122A. In this manner, molding compound is prevented from contactingeither interior surface 122I or exterior surface 122E of window 122A.Accordingly, molding 124A contacts only sides 122S of window 122A anddoes not extend over interior surface 122I or exterior surface 122E ofwindow 122A.

FIG. 7B is an enlarged cross-sectional view of the region VII of FIG. 6in accordance with another embodiment of the present invention. Thisembodiment is substantially similar with the embodiment illustrated inFIG. 7A with the exception that molding 124A includes exterior lockingfeature 225E and interior locking feature 225I.

As shown in FIG. 7B, exterior locking feature 225E extends over andcontacts a periphery of exterior surface 122E of window 122A. Similarly,interior locking feature 225I extends over and contacts a periphery ofinterior surface 122I of window 122A. Exterior and interior lockingfeatures 225E, 225I are flash, i.e., molding compound which is forcedbetween base 306A and exterior surface 122E and between base 504A andinterior surface 122I, respectively, during the transfer of the moldingcompound to the mold. However, control of flash may be difficultdepending upon the particular application.

FIG. 7C is an enlarged cross-sectional view of the region VII of FIG. 6in accordance with yet another embodiment of the present invention. Inaccordance with this embodiment, base 504A includes a pad 710 and base306A includes a pad 712. Pads 710, 712 are typically a compliantmaterial such a silicone. In one embodiment, pads 710, 712 are each 0.25millimeters (mm) thick.

As shown in FIG. 7C, pad 710 contacts a central region 122ICR ofinterior surface 122I of window 122. Central region 122ICR is surroundedby peripheral region 122IPR of interior surface 122I of window 122A. Inone embodiment, interior surface 122I is 8.5 mm square and peripheralregion 122IPR extends inward 1.0 mm from sides 122S of window 122A,i.e., central region 122ICR is located 1.0 mm from sides 122S of window122.

Similarly, pad 712 contacts a central region 122ECR of exterior surface122E of window 122A. Central region 122ECR is surrounded by peripheralregion 122EPR of exterior surface 122E of window 122A.

In one embodiment, exterior surface 122E is 8.5 mmm square andperipheral region 122EPR extends inward 1.0 mm from sides 122S of window122A, i.e., central region 122ECR is located 1.0 mm from sides 122S ofwindow 122.

Use of pads 710, 712 creates spaces between peripheral regions 122IPR,122EPR and bases 504A, 306A, respectively. Advantageously, moldingcompound fills these spaces during the transfer of the molding compoundinto the mold. As a result, interior locking feature 225I is formedbetween peripheral region 122IPR and base 504A and exterior lockingfeature 225E is formed between peripheral region 122EPR and base 306A.Further, since molding 124A, including interior and exterior lockingfeatures 225I, 225E, is formed during a single molding step, molding124A including interior and exterior locking features 225I, 225E isintegral, i.e., molding 124A, interior locking feature 225I and exteriorlocking feature 225E are all the same piece and are not a plurality ofseparate pieces connected together.

In FIGS. 7B, 7C, both interior and exterior locking features 225I, 225Eare illustrated. However, in an alternative embodiment, only interiorlocking feature 225I or exterior locking feature 225E is formed. As anexample, referring to FIG. 7C, only pad 710 or pad 712 is used resultingin the formation of only interior locking feature 225I or exteriorlocking feature 225E, respectively.

Although in FIGS. 7A, 7B and 7C, molding of first window 122A of theplurality of windows 122 in first molding 124A of the plurality ofmoldings 124 is discussed, in light of this disclosure, it is understoodthat the other windows 122 are molded in corresponding moldings 124simultaneously and in a similar manner.

FIG. 8 is a cross-sectional view of an array 800 of image sensorpackages 100 during assembly in accordance with the present invention.After molding windows 122 in molding compound, a molded window array 802is removed from the mold, i.e., is removed from lower mold half 300 andupper mold half 500 (see FIG. 6). Molded window array 802 includeswindows 122, which, in this embodiment, are supported by and molded incorresponding moldings 124. For example, first window 122A of theplurality of windows 122 is supported by and molded in first molding124A of the plurality of moldings 124. Each of the other windows 122 issimilarly supported by and molded in a corresponding molding 124.

Each of moldings 124 include a plurality of alignment notches 130. Forexample, molding 124A includes three alignment notches 130A of theplurality of alignment notches 130 although only one alignment notch130A is shown in the view of FIG. 8. Alignment notches 130 are formedby, and correspond to, tabs 304 of lower mold half 300 (see FIGS. 3 and4).

As shown in FIG. 8, array 800 includes a substrate 810. Substrate 810includes a plurality of individual substrates 102 integrally connectedtogether in an array format. Each of substrates 102 is delineated andseparated by a singulation street 812 which is located between adjacentsubstrates 102. For example, a first singulation street 812A of aplurality of singulation streets 812 separates a first substrate 102A ofthe plurality of substrates 102 from a second substrate 102B of theplurality of substrates 102. The other substrates 102 are similarlyseparated from adjacent substrates 102 by corresponding singulationstreets 812.

Substrates 102 include traces 104 and metallizations 109 on uppersurfaces 102U of substrates 102. Substrates 102 also includes vias 215extending through substrates 102 and traces 216, pads 217 on lowersurfaces 102L of substrate 102 which are not illustrated in FIG. 8 forpurposes of clarity. See vias 215, traces 216 and pads 217 of FIG. 2 forexample. In one embodiment, metalized vias along singulation streets 812are combined with conductive lands to provide LCC footprints.

Image sensors 106 are attached to corresponding substrates 102, and moreparticularly, to corresponding metallizations 109, by correspondingadhesive layers 108. For example, a first image sensor 106A of theplurality of image sensors 106 is attached to substrate 102A, and moreparticularly, to metallization 109A, by adhesive layer 108A. The otherimage sensors 106 are similarly attached.

During attachment, image sensors 106 are aligned to substrate 810 usingany one of a number of conventional alignment techniques, e.g., areoptically or mechanically aligned. In one embodiment, a pick and placemachine such as a MRSI 505 by MRSI Corp. of Chelmsford, Mass. is used toalign image sensors 106 to substrate 810. Of importance, this allowsimage sensors 106 to be precisely aligned to substrate 810 to withintight positional tolerances, e.g., to within 0.001 inches (0.025 mm).

Bond pads 112 of image sensors 106 are electrically connected tocorresponding traces 104 by corresponding bond wires 114. For example, abond pad 112B of the plurality of bond pads 112 is electricallyconnected to a corresponding trace 104B of the plurality of traces 104by a bond wire 114B of the plurality of bond wires 114. The other bondpads 112 are similarly connected.

An adhesive layer 126 is applied to bases 226 of each of moldings 124and to bridge sections 602. Adhesive layer 126 is applied using any oneof a number of conventional techniques, e.g., a B stage epoxy is appliedby screen printing or needle dispensing or, alternatively, a doublesided laminate adhesive tape is applied by pressure.

Instead of applying adhesive layer 126 directly to bases 226 of moldings124 and to bridge sections 602 as illustrated in FIG. 8, in analternative embodiment, adhesive layer 126 is applied to selectiveportions of an upper surface 810U of substrate 810, and moreparticularly, is applied over and extends slightly beyond singulationstreets 812 and is applied over a periphery 814 of substrate 810.

After application of adhesive layer 126, molded window array 802 isaligned with substrate 810 using any one of a number of conventionalalignment techniques, e.g., is optically or mechanically aligned. Ofimportance, molded window array 802 is precisely aligned with substrate810, and hence image sensors 106, to within tight positional tolerance,e.g., to within 0.001 inches (0.025 mm).

After alignment, molded window array 802 is moved and brought intoabutting contact with substrate 810 such that adhesive layer 126contacts both molded window array 802 and substrate 810. If necessary,e.g., if adhesive layer 126 is a B staged epoxy, adhesive layer 126 iscured. In this manner, molded window array 802 is attached to substrate810 by adhesive layer 126.

FIG. 9 is a cross-sectional view of array 800 of image sensor packages100 of FIG. 8 at a later stage of fabrication in accordance with thepresent invention. After molded window array 802 is attached tosubstrate 810, in one embodiment, each molding 124 or substrate 102 ismarked, for example with ink, to identify the part number associatedwith image sensor package 100. In accordance with this embodiment, alower surface 810L of substrate 810 is populated with interconnectionballs 218, e.g., on traces (not shown).

Array 800 is then singulated into a plurality of individual image sensorpackages 100 (see FIGS. 1, 2) by separating array 800 along singulationstreets 812. Singulation can be accomplished using any one of a numberof conventional singulation techniques, e.g. by laser cutting ormechanical sawing through substrate 810, adhesive layer 126 and bridgesections 602. In one embodiment, periphery 814 and the overlyingadhesive layer 126 and overlying section of molded window array 802 arealso trimmed during singulation.

In accordance with an alternative embodiment of the present invention,substrate 810 is a snap straight substrate, i.e., is a substratedesigned to snap along singulation streets 812 on bending of substrate810. Snap straight substrates, typically ceramic, are well known tothose of skill in the art and are not discussed further to avoiddetracting from the principles of the invention.

In accordance with this embodiment, bridge sections 602 of molded windowarray 802 and adhesive layer 126 are also designed to snap along withsubstrate 810 along singulation streets 812. Bridge sections 602 areformed of a molding compound which is sufficiently brittle to snap. Inother embodiments, bridge sections 602 are fabricated to have lessstrength than the remainder of molded window array 802 to facilitatesnapping of bridge sections 602 as discussed in greater detail belowwith respect to FIGS. 10A, 10B.

FIG. 10A is an enlarged cross-sectional view of the region X of FIG. 6in accordance with this embodiment of the present invention. As shown inFIG. 10A, upper mold half 500 includes a tab 1002 which extends fromupper mold half 500 downwards towards lower mold half 300. Similarly,lower mold half 300 includes a tab 1004 which extends from lower moldhalf 300 upwards towards upper mold half 500.

Tabs 1002 and 1004 are located directly across from one another anddefine a narrow portion 1006 of bridge section 602A. Narrow portion 1006has a width WNP less than a width WWP of a second wide portion 1008 ofbridge section 602A. Since narrow portion 1006 has less width than wideportion 1008, narrow portion 1006 has less mechanical strength than wideportion 1008. Thus, referring to FIGS. 9 and 10A together, bridgesection 602A preferentially snaps apart at narrow portion 1006 whensubstrate 810 is snapped along a singulation street 812.

FIG. 10B is an enlarged perspective view, partially in cross-section, ofthe region X of FIG. 6 in accordance with an alternative embodiment ofthe present invention. In FIG. 10B, upper and lower mold halves 500, 300are not illustrated for purposes of clarity.

In this embodiment, bridge section 602A includes a finger portion 1010,which is sometimes called webbing. Finger portion 1010 includes aplurality of fingers 1012 extending between body portions 1014 and 1016of bridge section 602A. A space 1018 exists between each of fingers 1012along the depth of bridge section 602A (i.e. along the Z axis of FIG.10B) and between body portions 1014, 1016 in the horizontal direction(i.e., along the X axis of FIG. 10B). To illustrate, a first space 1018Aof the plurality of spaces 1018 exists between first and second fingers1012A, 1012B of the plurality of fingers 1012 and between body portions1014, 1016.

In one embodiment, each of fingers 1012 has a width WFP (along the Yaxis of FIG. 10B) less than a width WBP of body portions 1014, 1016. Byforming finger portion 1010 with fingers 1012 and spaces 1018, fingerportion 1010 has less mechanical strength than body portions 1014, 1016.Thus, referring to FIGS. 9 and 10B together, bridge section 602Apreferentially snaps apart at finger portion 1010 when substrate 810 issnapped along a singulation street 812.

Although only a single bridge section 602A of the plurality of bridgesections 602 is described and illustrated in each of the embodiments ofFIGS. 10A, 10B, the other bridge sections 602 are similar in structureand function so are not described further.

By forming a plurality of packages 100 simultaneously, severaladvantages are realized. One advantage is that it is less laborintensive to handle and process a plurality of packages 100simultaneously rather than to handle and process each package 100 on anindividual basis. Another advantage is that usage of materials is moreefficient when an array of packages 100 is fabricated. By reducing laborand using less material, the cost associated with each package 100 isminimized. However, in light of this disclosure, those of skill in theart will recognize that packages 100 can also be manufactured on anindividual basis if desired.

FIG. 11 is a perspective view, partially cutaway and partially exploded,of an image sensor package 1100 in accordance with another embodiment ofthe present invention. FIG. 12 is a cross-sectional view of package 1100taken along the line XII—XII of FIG. 11. Referring to FIGS. 11 and 12together, package 1100 is similar in many respects with package 100 ofFIGS. 1 and 2 and the discussion above in reference to package 100 isincorporated herein. To avoid detracting from the principals of theinvention, only the relevant differences between packages 1100 and 100are discussed below.

Molding 124C of package 1100 includes a lens holder extension portion1102. Molding 124C including lens holder extension portion 1102 isintegral, i.e., is one piece and not a plurality of separate piecesconnected together. Lens holder extension portion 1102 extends upwards,e.g. in a first direction perpendicular to exterior surface 122E ofwindow 122, from window 122. Lens holder extension portion 1102 includesan interior cylindrical surface 1104 which defines an aperture 1106. Alongitudinal axis 1208 of aperture 1106 is perpendicular to a planeparallel to window 122 and, more particularly, is perpendicular toexterior and interior surfaces 122E, 122I of window 122 in thisembodiment. Aperture 1106 extends upward from window 122 such thatwindow 122 is exposed through aperture 1106.

To facilitate attachment of an optical element 1210 such as a lens(hereinafter lens 1210), interior cylindrical surfaced 1104 is threaded.Stated another way, aperture 1106 is a female threaded aperture.

Lens 1210 is supported in a support 1112, hereinafter lens support 1112.Lens support 1112 is a cylindrical annulus having an interiorcylindrical surface 1214 which defines an aperture 1216. Lens 1210 ispositioned in aperture 1216 such that lens 1210 and lens support 1112have a common longitudinal axis 1218.

Lens support 1112 has an exterior cylindrical surface 1120, which isthreaded. Stated another way, lens support 1112 is male threaded. Ofimportance, the threading of exterior cylindrical surface 1120corresponds with the threading of interior cylindrical surface 1104allowing threaded attachment of lens support 1112 to molding 124C.

To attach lens support 1112 to molding 124C, lens support 1112 ispositioned above molding 124C such that longitudinal axes 1208, 1218 aresubstantially aligned as best shown in FIG. 12. Lens support 1112 isthreaded into aperture 1106 so that exterior cylindrical surface 1120 isthreadedly attached to interior cylindrical surface 1104 of molding124C.

Advantageously, lens 1210 is readily adjusted relative to image sensor106 by rotating lens support 1112. More particularly, lens support 1112is rotated around longitudinal axis 1218 in a first direction, e.g.,clockwise looking down at lens support 1112, to move lens support 1112and lens 1210 towards image sensor 106. Conversely, lens support 1112 isrotated around longitudinal axis 1218 in a second direction opposite thefirst direction, e.g., counterclockwise looking down at lens support1112, to move lens support 1112 and lens 1210 away from image sensor106. In this manner, lens support 1112 is rotated until radiationpassing through lens 1210 is properly focused on active area 110 ofimage sensor 106. Once proper focus is attained, lens support 1112 isprevented from unintentional rotation. For example, adhesive is appliedto secure lens support 1112 to molding 124C.

Recall that in the prior art, the lens assembly was typically attacheddirectly to the larger substrate, such as a printed circuit motherboard, after the image sensor assembly was attached to the largersubstrate. A large tolerance was associated with attachment of the lensassembly in this manner. However, it is important to reduce tolerancesto optimize performance of the image sensor assembly.

Further, the lens assembly of the prior art typically had to be adjustedby moving the lens assembly relative to the larger substrate, forexample with adjustment screws. Undesirably, this was labor intensivewhich increased the cost of the electronic device which used the imagesensor assembly.

In addition, the lens assembly of the prior art was sometimesinadvertently moved relative to the image sensor which caused defocusingand defective operation of the image sensor. For example, the lensassembly was sometimes bumped during assembly or servicing of theelectronic device which used the image sensor assembly. As anotherexample, the lens assembly moved due to warpage of the substrate.

Advantageously, package 1100 in accordance with the present inventioneliminates these problems of the prior art. In particular, since molding124C is precisely positioned to within tight tolerance of image sensor106, the position both horizontally and vertically in the view of FIG.12 of lens 1210 with respect to image sensor 106 is also precise towithin tight tolerance, e.g., to within 0.001 in. (0.025 mm). Moreparticularly, the optical axis of lens 1210 is precisely aligned withthe optical center of active area 110 of image sensor 106. Reducingtolerance in the position of lens 1210 with respect to image sensor 106improves performance of package 1100 compared to prior art image sensorassemblies.

Further, lens 1210 is adjusted relative to image sensor 106 simply byrotating lens support 1112 thus readily allowing focusing of radiationon active area 110 of image sensor 106. Advantageously, this focusing isperformed during fabrication of package 1100 before assembly to thelarger substrate. Thus, the prior art requirement of focusing the lensassembly during assembly of the larger substrate is eliminated. As aresult, the costs associated with package 1100 are lower than thoseassociated with prior art image sensor assemblies.

Further, since lens support 1112 and lens 1210 are integrated intopackage 1100, there is essentially no possibility of inadvertentlymoving lens 1210 relative to image sensor 106. Thus, the prior artpossibility of bumping the lens assembly or otherwise having the lensassembly move and defocus the radiation is eliminated.

Fabrication of package 1100 is similar in many respects with fabricationof package 100 of FIGS. 1 and 2 and the discussion above regarding thefabrication of package 100 is incorporated herein. To avoid detractingfrom the principals of the invention, only the relevant differencesbetween the fabrication of package 1100 and the fabrication of package100 are discussed below.

FIG. 13 is a cross-sectional view of a molded window array 1300 inaccordance with one embodiment of the present invention. Molded windowarray 1300 is formed using a multi-piece mold, e.g., a three or fourpiece mold. In one particular embodiment, apertures 1106 are formed bymolding around threaded plugs, which are then unscrewed from moldedwindow array 1300.

Molded window array 1300 of FIG. 13 is substantially similar to moldedwindow array 802 of FIG. 8 except that each molding 124C of moldedwindow array 1300 includes a lens holder extension portion 1102 and apocket 1302 for supporting a window 122. For example, a first molding124C1 of the plurality of moldings 124C includes a first lens holderextension portion 1102A of the plurality of lens holder extensionportions 1102 and a first pocket 1302A of the plurality of pockets 1302.The other moldings 124C have similar corresponding lens holder extensionportions 1102 and pockets 1302 so are not discussed further.

FIG. 14 is an enlarged cross-sectional view of the region XIV of FIG. 13in accordance with this embodiment of the present invention. Referringto FIG. 14, pocket 1302A is shaped to fit and support a window 122B1(window 122B1 is not illustrated in FIG. 13 for purposes of clarity).More particularly, pocket 1302A is essentially the same size and shapeas window 122B1. Pocket 1302A is defined by sides 1404 of molding 124C1which correspond to sides 122S of window 122B1. Pocket 1302A is furtherdefined by a shelf 1406 of molding 124C1, which is perpendicular tosides 1404 and extends inwards from sides 1404. Shelf 1406 correspondsto a peripheral region 122EPR of an exterior surface 122E of window122B1.

In accordance with this embodiment, after molded window array 1300, andin particular molding 124C1, is fabricated, window 122B1 is secured inpocket 1302A. As an illustration, window 122B1 is placed into pocket1302A and an adhesive is applied to secure window 122B1 in place.Advantageously, this allows window 122B1 to be kept in a protectivewrapper until just before the assembly of molded window array 1300 tothe substrate, for example, to substrate 810 of FIG. 8. By waiting tosecure window 122B1 to molding 124C1 just before the assembly of moldedwindow array 1300 to the substrate, possible contamination of window122B1, for example during shipment of molded window array 1300, isavoided.

Although securing of a first window 122B1 of a plurality of windows 122to first pocket 1302A of the plurality of pockets 1302 is discussedabove, in light of this disclosure, it is understood that the otherwindows 122 are secured in corresponding pockets 1302 in a similarmanner.

Referring again to FIG. 13, in an alternative embodiment, instead offorming pockets 1302, windows 122 are molded into molded window array1300 during the fabrication of molded window array 1300. Molding ofwindows 122 in accordance with this embodiment is substantially similarto molding of windows 122 as discussed in reference to the embodimentsof FIGS. 7A, 7B and 7C, the discussion of which is incorporated herein.

FIG. 15 is an exploded perspective view of an image sensor package 1500in accordance with another embodiment of the present invention. FIG. 16is a cross-sectional view of package 1500 taken along the line XVI—XVIof FIG. 15. Referring to FIGS. 15 and 16 together, package 1500 issimilar in many respects with package 100 of FIGS. 1 and 2 and thediscussion above in reference to package 100 is incorporated herein. Toavoid detracting from the principals of the invention, only the relevantdifferences between packages 1500 and 100 are discussed below.

Package 1500 includes a snap lid 1502 which snaps onto a molding 124D ofpackage 1500 to hold a window 122C in place. In one embodiment, snap lid1502 is a low cost molded part. Snap lid 1502 includes a plurality ofalignment notches 130 used to align the lens (not shown) to image sensor106.

Snap lid 1502 includes a compression ring section 1504 which pressesagainst window 122C to hold window 122C in place as discussed furtherbelow. Snap lid 1502 further includes a snap 1506 extending downwardsfrom compression ring section 1504. Snap 1506 snaps onto a correspondinglocking feature 1508 of molding 124D to attach snap lid 1502 to molding124D.

In this embodiment, compression ring section 1504 is rectangular andincludes a rectangular central aperture 1510. A central region of window122C (see central region 122CR of FIGS. 18A and 18B for example) isexposed to the ambient environment through aperture 1510. During use,radiation passes through aperture 1510, though window 122C and strikesactive area 110 of image sensor 106.

Snap 1506 extends downwards from edges of compression ring section 1504towards molding 124D, perpendicular to a plane defined by compressionring section 1504. As shown in FIG. 16, snap 1506 includes an inwardlyextending tab 1612, e.g., a hook-like feature, which is attached tolocking feature 1508 of molding 124D.

In this embodiment, locking feature 1508 of molding 124D is shaped as arectangular bar extending outward in a plane parallel to compressionring section 1504 from molding 124D along all four sides of molding124D. Locking feature 1508 includes a lip 1614. Tab 1612 is in abuttingcontact with lip 1614 such that snap 1506 encompasses and holds lockingfeature 1508 thus securing snap lid 1502 to molding 124D.

FIG. 17 is a cross-sectional view of package 1500 illustrating theattachment of snap lid 1502 to molding 124D in accordance with thisembodiment of the present invention. After window 122C is placed inmolding 124D, snap lid 1502 is aligned with molding 124D. Once aligned,snap lid 1502 is at a position 1700. At position 1700, snap 1506 islaterally aligned to extend around locking feature 1508. Further, atposition 1700, snap lid 1502 is in its relaxed state, i.e., is notstressed.

After alignment, snap lid 1502 is snapped onto molding 124D. Tofacilitate this snapping, snap lid 1502 is pressed towards molding 124D.This causes snap 1506 to slide against locking feature 1508. Tofacilitate this sliding, snap 1506 includes a taper 1702 which slidesagainst locking feature 1508.

As taper 1702 slides against locking feature 1508, snap 1506 isdistorted and bent away from compression ring section 1504. Thisproduces stress in snap lid 1502 which causes tab 1612 to press inwardagainst locking feature 1508. To illustrate, at a position 1704(indicated in dashed lines for clarity), snap 1506 is distorted and bentand tab 1612 is pressing inward against locking feature 1508.

Snap lid 1502 is pressed towards molding 124D until tab 1612 reaches lip1614 of locking feature 1508. Upon tab 1612 reaching lip 1614, stress insnap lid 1502 causes snap 1506 to snap inwards such that tab 1612engages lip 1614 as shown in FIG. 16. Advantageously, stress created insnap lid 1502 during attachment firmly presses snap 1506 around lockingfeature 1508 so that snap lid 1502 is securely attached to molding 124D.When attached, snap lid 1502 holds window 122 in place as discussed inreference to FIGS. 18A and 18B.

FIG. 18A is an enlarged cross-sectional view of the region XVIII of FIG.16 in accordance with this embodiment of the present invention. As shownin FIG. 18A, window 122C is supported in a pocket 1800 defined by sides1802 and a shelf 1804 of molding 124D. Sides 1802 of molding 124D aresubstantially the same width (in the vertical direction of the view ofFIG. 18A) as sides 122S of window 122C. Shelf 1804 is perpendicular tosides 1802 and extends inward from sides 1802.

In accordance with this embodiment, after molding 124D is fabricated,window 122C is placed in pocket 1800. After placement of window 122C inpocket 1800, shelf 1804 contacts and supports a peripheral region 122IPRof interior surface 122I of window 122C. Snap lid 1502 is secured inplace as described in reference to FIG. 17. Once secured, snap lid 1502,and more particularly compression ring section 1504, contacts andpresses against a peripheral region 122EPR of exterior surface 122E ofwindow 122C.

Of importance, window 122C is sandwiched between molding 124D and snaplid 1502. In this manner, window 122C is held in place. Advantageously,use of snap lid 1502 allows window 122C to be kept in a protectivewrapper until window 122C is needed. For example, window 122C is kept ina protective wrapper to avoid contamination or scratching of window122C.

As a further advantage, use of snap lid 1502 allows window 122C to beeasily removed. In light of this disclosure, those of skill in the artwill understand that snap 1506 (FIG. 16) is pulled away from molding124D to unlock tab 1612 from lip 1614 and thus allow removal of snap lid1502 from molding 124D. Once removed, window 122C is easily cleaned,treated or replaced with a different window. As an example of a suitablewindow 122C, window 122C in FIG. 18A includes a first layer 1810 such asplanar glass and a second layer 1812 such as an infrared filter.However, in other embodiments, window 122C is a single layer such asingle piece of planar glass.

Further, in some applications, it may be desirable to prevent window122C from being removable. To prevent window 122C from being removable,in one embodiment, window 122C is permanently secured to molding 124D.For example, adhesive is applied to adhere window 122C in pocket 1800before snap lid 1502 is secured.

In reference to FIG. 17, the attachment of a single snap lid 1502 to asingle molding 124D is described. However, in an alternative embodiment,molding 124D is fabricated simultaneously with a plurality of moldings124D as part of a molded window array similar to molded window array 802of FIG. 8. Windows 122C and snap lids 1502 are attached to moldings 124Dwhile moldings 124D are still part of the molded window array. Thisattachment occurs while the molded window array is separate from asubstrate, e.g., substrate 810 of FIG. 8. Alternatively, this attachmentoccurs after the molded window array is attached to a substrate, e.g.,substrate 810 of FIG. 9.

As a further alternative, molding 124D is singulated from the othermoldings 124D of the molded window array, window 122 and snap lid 1502attached, and molding 124D attached to the individual substrate, e.g.substrate 102 of FIG. 15.

FIG. 18B is an enlarged cross-sectional view of the region XVIII ofpackage 1500 of FIG. 16 in accordance with an alternative embodiment ofthe present invention. The embodiment of FIG. 18B is substantiallysimilar to the embodiment of FIG. 18A with the exception that sides1802A of molding 124D1 are shorter than sides 122S of window 122C andcompression ring section 1504A of snap lid 1502A includes a pocket 1820.

Pocket 1820 of snap lid 1502A is symmetric with pocket 1800A of molding124D1. Pocket 1820 is defined by sides 1822A and a shelf 1824 of snaplid 1502A. Shelf 1824 is perpendicular to sides 1822A and extends inwardfrom sides 1822A. Sides 1802A and 1822A lie on a common plane and thecombined width (in the vertical direction in the view of FIG. 18B) ofsides 1802A and 1822A is substantially equal to the width of sides 122Sof window 122C. Shelfs 1824, 1804 press on peripheral regions 122EPR,122IPR of exterior and interior surfaces 122E, 122I, respectively, ofwindow 122. In this manner, window 122C is supported in pockets 1800Aand 1820 and held in place.

This application is related to: Webster, U.S. patent application Ser.No. 09/457,505, filed Dec. 8, 1999, now U.S. Pat. No. 6,455,774, issuedSep. 24, 2002, entitled “MOLDED IMAGE SENSOR PACKAGE”; Webster, U.S.patent application Ser. No. 09/457,513, filed Dec. 8, 1999, entitled“MOLDED IMAGE SENSOR PACKAGE HAVING LENS HOLDER”; Glenn et al., U.S.patent application Ser. No. 09/457,515, entitled “METHOD OF ASSEMBLING ASNAP LID IMAGE SENSOR PACKAGE”; Glenn et al., U.S. patent applicationSer. No. 09/458,033, filed Dec. 8, 1999, now U.S. Pat. No. 6,266,197,issued Jul. 24, 2001, entitled “MOLDED WINDOW ARRAY FOR IMAGE SENSORPACKAGES”; and Glenn et al., U.S. patent application Ser. No.09/457,517, filed Dec. 8, 1999, now U.S. Pat. No. 6,389,687, issued May21, 2002, entitled “METHOD OF FABRICATING IMAGE SENSOR PACKAGES IN ANARRAY”; which are all herein incorporated by reference in theirentirety.

The drawings and the forgoing description gave examples of the presentinvention. The scope of the present invention, however, is by no meanslimited by these specific examples. Numerous variations, whetherexplicitly given in the specification or not, such as differences instructure, dimension, and use of material, are possible. The scope ofthe invention is at least as broad as given by the following claims.

1. A method of forming an image sensor package comprising: coupling animage sensor to a substrate; forming an optical lid, said optical lidcomprising: an optical element; and a snapping feature; and couplingsaid optical lid to said substrate comprising: mounting a moldingcomprising a locking feature to said substrate; and snapping saidsnapping feature to said locking feature.
 2. The method of claim 1wherein said substrate is a ceramic substrate.
 3. The method of claim 1wherein said image sensor is selected from the group consisting of aCMOS image sensor device, a charge coupled device and a pyroelectricceramic on CMOS device.
 4. The method of claim 1 wherein said opticalelement comprises a lens.
 5. The method of claim 1 wherein said opticalelement comprises a window.
 6. The method of claim 5 wherein said windowcomprises a filter.
 7. The method of claim 1 wherein said opticalelement consists of a lens.
 8. The method of claim 1 wherein said imagesensor package is a leadless chip carrier (LCC) package.
 9. The methodof claim 1 wherein said molding is mounted to said substrate with anadhesive layer.
 10. The method of claim 9 wherein said molding, saidsubstrate and said adhesive layer form an enclosure, said image sensorbeing located in said enclosure.
 11. The method of claim 1 wherein saidoptical lid is coupled to said substrate by an adhesive layer.
 12. Amethod of forming an image sensor package comprising: forming a meansfor supporting an optical element, said means for supporting comprising:a threaded interior cylindrical surface defining an aperture; and apocket for supporting said optical element; placing said optical elementin said pocket; threadedly attaching a threaded exterior cylindricalsurface of a support to said threaded interior cylindrical surface ofsaid means for supporting; and coupling said means for supporting to afirst surface of a substrate, said substrate comprising means forelectrically connecting said image sensor package to a printed circuitboard, said means for electrically connecting being coupled to a secondsurface of said substrate.
 13. The method of claim 12 wherein saidoptical element comprises a lens.
 14. The method of claim 12 whereinsaid substrate comprises a ceramic substrate, said image sensor packagebeing an leadless chip carrier (LCC) package.